In a machine tool, a drive member such as a lead-screw arrangement is commonly coupled drivingly with a movable element and driven by motor means such as a DC motor or stepping motor energized by a feed signal to achieve a given movement of the movable element. In a numerical-controlled (NC) machine tool, the feed signal is a stream of pulses based upon digital commands preprogrammed on a record medium so that the desired movement may be performed as accurately as possible in accordance with the programmed commands. Such drive systems, however, commonly entail conversion of electrical to mechanical signals and further conversion of rotary mechanical to longitudinal signals or displacements. Thus, a mechanical error unavoidably develops in the stage of conversion due, for example, to an error in the lead or pitch of a lead screw and a backlash in various components. As a result, a precision electrical command is not accurately reproduced in a desired movement of the movable element. These errors are inherent in each particular machine tool and cannot generally be compensated for by a process of preprogramming with the conventional systems.